Histograms ... where to actually apply corrections.

[fresnosmooth]

I was thinking about this today. If you were reading a histogram to figure out where you are getting KR aren't you actually correcting "too late".
My thinking is that the PCM reacts to corrections, so technically aren't things like fuel trims, ignition, etc a "reaction" or technically speaking a correction for what happened ... in the previously recorded cell? (maybe even before that ...?)

I don't know if this is true, just thinking ... corrections can't be made for a bad target immediately, only re-actively, so wouldn't one tune to "lead" a little?

[Ben C]

It of course depends on what you are logging and looking at correcting.. I'm. The spark example what you said is correct. Simply adjusting the spark table by the kr recorded is silly, as the decay rate of knock retard means timing will be pulled for too long..
you do need to think about what you are doing, as you have just done!

[mowton]

Another tip for KR correction is to start with removing half the total knock retard you are seeing in each particular cell. Some say take your knock graph and copy/Subtract from your Hi Octane spark table. But that is too much, too fast for me. Most times just removing half of the spark value will preclude the total knock from occurring.

And in agreement with the look ahead strategy, I will always "smooth in" the cell reduction by selecting 2 cells around the cells that were reduced and interpolate across. This slightly lowers the cells touching the knocking cells for a little lead in reduction.

In addition, always make sure that you have selected for view the + (highest value) and not the A (Average) because the latter will give you a much lower value as it is averaging the knock values over the entire count assigned to that cell over the entire log.

Ed M

[fresnosmooth]

That is awesome advice thank you both very much.
Cheers Ben, thank you Ed!!